Implement 'topLevelLibraryDeclarations' getter to return all libraries with exported top-level decl…

pkg/analyzer/test/src/dart/analysis/driver_test.dart

Index: pkg/analyzer/test/src/dart/analysis/driver_test.dart
diff --git a/pkg/analyzer/test/src/dart/analysis/driver_test.dart b/pkg/analyzer/test/src/dart/analysis/driver_test.dart
index 6b4231e490ec7c327ce4c1ba063430e9e270cf38..695664931e527af3873039755de9bd2526d8333f 100644
--- a/pkg/analyzer/test/src/dart/analysis/driver_test.dart
+++ b/pkg/analyzer/test/src/dart/analysis/driver_test.dart
@@ -16,6 +16,7 @@ import 'package:analyzer/src/dart/analysis/byte_store.dart';
 import 'package:analyzer/src/dart/analysis/driver.dart';
 import 'package:analyzer/src/dart/analysis/file_state.dart';
 import 'package:analyzer/src/dart/analysis/status.dart';
+import 'package:analyzer/src/dart/analysis/top_level_declaration.dart';
 import 'package:analyzer/src/error/codes.dart';
 import 'package:analyzer/src/generated/engine.dart' show AnalysisOptionsImpl;
 import 'package:analyzer/src/generated/source.dart';
@@ -1137,6 +1138,39 @@ var A = B;
     expect(allStatuses[1].isIdle, isTrue);
   }
 
+  test_topLevelLibraryDeclarations() async {
+    var a = _p('/test/lib/a.dart');
+    var b = _p('/test/lib/b.dart');
+    var c = _p('/test/lib/c.dart');
+    var d = _p('/test/lib/d.dart');
+
+    provider.newFile(a, 'class A {}');
+    provider.newFile(b, 'export "a.dart", class B {}');
+    provider.newFile(c, 'import "d.dart"; class C {}');
+    provider.newFile(d, 'class D {}');
+
+    driver.addFile(a);
+    driver.addFile(b);
+    driver.addFile(c);
+    // Don't add d.dart, it is referenced implicitly.
+
+    List<TopLevelLibraryDeclarations> libraries =
+        await driver.topLevelLibraryDeclarations;
+    expect(libraries, hasLength(4));
+
+    void assertDeclarations(String path, List<String> expectedNames) {
+      TopLevelLibraryDeclarations library =
+          libraries.singleWhere((l) => l.source.fullName == path);
+      expect(library.declarations.map((d) => d.name),
+          unorderedEquals(expectedNames));
+    }
+
+    assertDeclarations(a, ['A']);
+    assertDeclarations(b, ['A', 'B']);
+    assertDeclarations(c, ['C']);
+    assertDeclarations(d, ['D']);
+  }
+
   ClassDeclaration _getClass(CompilationUnit unit, String name) {
     for (CompilationUnitMember declaration in unit.declarations) {
       if (declaration is ClassDeclaration) {